Welding system and method of welding

ABSTRACT

A three stage power source for an electric arc welding process comprising an input stage having an AC input and a first DC output signal; a second stage in the form of an unregulated DC to DC converter having an input connected to the first DC output signal and converts the first DC output signal to a second DC output signal of the second stage; and a third stage to convert the second DC output signal to a welding output for welding wherein the input stage and the second stage are assembled into a first module within a first housing structure and the third stage is assembled into a second module having a separate housing structure connectable to the first module with long power cables. The second module also includes wire feeding systems and electronics.

PRIORITY

The present application is a continuation in part of U.S. patentapplication Ser. No. 11/051,196 filed on Feb. 7, 2005, which isincorporated herein by reference in its entirety.

TECHNICAL FIELD OF THE INVENTION

Embodiments of the present invention relates to the field of electricarc welding and more particularly to an improved power source for suchwelding with improved performance and reliability.

BACKGROUND OF INVENTION

Welding systems which use a welding power supply and a wire feeder andgenerally known. In these systems, the welding power supply outputs awelding current signal to the wire feeder which directs the signal to acontact tip and ultimately a welding electrode. However, in certainapplications the distance between the welding power supply and the wirefeeder can be great, requiring very long cables. This can adverselyaffect the performance of the welding system because it can greatlyincrease the inductance of the welding circuit. This is particularlyproblematic when using pulse welding processes which require quickresponsiveness. Furthermore, the cables can interfere with the workplaceand can break or be damaged. Therefore, there is a need for a weldingsystem which can be used where long distances are in play, but highlyresponsive welding is needed.

Further limitations and disadvantages of conventional, traditional, andproposed approaches will become apparent to one of skill in the art,through comparison of such approaches with embodiments of the presentinvention as set forth in the remainder of the present application withreference to the drawings.

SUMMARY OF THE INVENTION

Embodiments of the present invention include welding systems having apower source component and a power conversion/wire feeding component.The power source component converts an input power from a utility orgenerator source to a non-welding power which is then sent to the powerconversion/wire feeding component which converts the non-welding powerto a welding current, and controls operation of the wire feed. Each ofthe components are located remote from each other, but the systemresponsiveness and operation is not compromised because the powerconversion/wire feeding component is located near the welding operation.Embodiments of the present invention, allow for the elimination of senseleads, while at the same time improving system performance.

BRIEF DESCRIPTION OF DRAWINGS

The above and/or other aspects of the invention will be more apparent bydescribing in detail exemplary embodiments of the invention withreference to the accompanying drawings, in which:

FIG. 1 is a block diagram illustrating a three stage power source anddisclosing an embodiment of three stage power source improved by theinvention;

FIG. 2 and FIG. 3 are block diagrams similar to FIG. 1 disclosingfurther embodiments of the three stage power source;

FIGS. 4-8 are partial block diagrams illustrating a three stage powersource with different first stage embodiments;

FIG. 9 is a block diagram showing the last two stages of the three stagepower source wherein the output stage provides AC welding current;

FIG. 9A is a block diagram of a waveform technology control circuit foruse in the three stage power source illustrated in FIG. 9, together withgraphs showing three welding waveforms;

FIG. 10 is a block diagram illustrating a second and third stage of athree stage power source wherein the output stage is DC welding current;

FIG. 11 is a block diagram illustrating the topography of the threestage power source for creating current suitable for electric arcwelding with two separate controller control voltage supplies;

FIG. 12 is a block diagram illustrating a specific three stage powersource employing the topography to which the present invention isdirected;

FIGS. 13-16 are wiring diagrams illustrating four different circuits forcorrecting the power factor in the first stage of the three stage powersource;

FIG. 17 is a combined block diagram and wiring diagram illustrating anexemplary embodiment of the unregulated inverter constituting the novelsecond stage of a three stage power source to which the presentinvention is directed;

FIGS. 18-21 are wiring diagrams showing several inverters used as thesecond stage unregulated, isolation inverter comprising the novel aspectof the three stage power source to which the present invention isdirected;

FIG. 22 is as wiring diagram describing the modularized three stagepower source of the present invention;

FIG. 23 is a wiring diagram of a standard chopper used as the outputmodule of the invention disclosed in FIG. 22;

FIG. 24 is a standard STT circuit used for the output module of theinvention illustrated in FIG. 22;

FIG. 25 is a novel dual mode chopper circuit forming another aspect ofthe present invention and usable as the output module of the inventiondisclosed in FIG. 22;

FIG. 26 is a wiring diagram of a prior art output circuit for obtainingAC welding current which is improved by the novel chopper circuit ofFIG. 25;

FIG. 27 is a detailed wiring diagram of the output chopper as shown inFIG. 23 with waveform technology control of the power switch and with acommonly used soft switching circuit for the power switch;

FIG. 28 is a combined block diagram and wiring diagram illustrating oneadvantage of the embodiment shown in FIG. 22;

FIG. 29 is a combined block diagram and wiring diagram illustratingstill a further advantage of the embodiment illustrated in FIG. 22;

FIG. 30 is a schematic representation of the novel three stage powersource combined with a submerged arc welding process;

FIG. 31 is a partial pictorial view illustrating a cored electrode whichis preferably used in the combination methods schematically illustratedin FIGS. 30 and 32-41;

FIG. 32 is a schematic representation of two novel three stage powersources combined with a tandem welding process, which process isillustrated as a submerged arc process;

FIG. 33 is a schematic representation of the novel three stage powersource combined with a TIG welding process either AC or DC;

FIG. 34 is a schematic representation of the novel three stage powersource combined with a MIG welding process, either AC or DC;

FIG. 35 is a current diagram of an AC output welding signal generated bythe novel three stage power source or the novel dual mode chopper of thepresent invention;

FIG. 36 is a current diagram of a DC output welding signal generated bythe novel three stage power source or the novel dual mode chopper of thepresent invention, which signal can be either negative or positive;

FIG. 37 is a schematic representation of the novel dual mode chopper inthe three stage power source combined with a MIG welding process, eithersubmerged arc or otherwise;

FIG. 38 is a schematic representation of the novel dual mode chopper ofthe present invention as an output of the novel three stage power sourcecombined with a TIG welding process, either AC or DC;

FIG. 39 is a schematic representation of the novel dual mode chopperwith a generic DC input signal combined with a MIG welding process;

FIG. 40 is a schematic representation of the novel dual mode chopper asillustrated in FIG. 39 wherein the illustrated MIG welding process is asubmerged arc process;

FIG. 41 is a schematic representation of the novel dual mode chopper ofthe present invention, as illustrated in FIGS. 39-40, in combinationwith a TIG welding process, either AC or DC; and

FIG. 42 is a diagrammatical representation of a welding system which canbe used with embodiments of the power supply shown in FIGS. 1-41;

FIG. 43 is a schematic representation of the system of FIG. 22 in ahousing;

FIG. 44 is a schematic representation of a welding system in accordancewith an exemplary embodiment of the present invention;

FIG. 45 is a schematic representation of another welding system inaccordance with an exemplary embodiment of the present invention; and

FIG. 46 is a diagrammatical representation of an exemplary weldingsystem and operation using a system consistent with the embodimentsshown in FIG. 44 or 45.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Exemplary embodiments of the invention will now be described below byreference to the attached Figures. The described exemplary embodimentsare intended to assist the understanding of the invention, and are notintended to limit the scope of the invention in any way. Like referencenumerals refer to like elements throughout.

Exemplary embodiments of the present invention are directed to weldingsystems which use wire feeding mechanisms electrically coupled to thepower supply. For example, exemplary embodiments of present inventioncan be used for GMAW type welding. It should be noted that embodimentsof the present invention are not limited by the operation and topologyof the power generation and wire feeding mechanisms. That is,embodiments of the present invention can be used with many differenttypes of wire feeder and power supply topologies, including, forexample, two-stage or three-stage topologies. This will be furtherexplained below, after the following discussion which is generallyrelated to a three-stage type power supply of the type that can beimplemented in the embodiments of the present invention. That is, thefollowing discussion related to FIGS. 1 through 41 is directed toexplain the construction and operation of a three-stage power supply,and the overall construction and topologies discussed below areexemplary of the types of components and operations that can beimplemented with embodiments of the present invention, with theunderstanding that the final welding current output stage of the weldingsystem is placed within a wire feeder and it is not within the housingof the remaining power supply components. This will be explained furtherwith regard to FIGS. 41 through 45. With that understanding, thefollowing discussion regarding an exemplary three-stage power supply isprovided.

An exemplary power source topology that can be used with embodiments ofthe present invention is a three-stage topology, examples of which areshown and discussed below. An exemplary three stage power source has aninput stage for converting an AC signal into a first DC output bus. Thisoutput bus has a fixed voltage level and is directed to the input of asecond stage best shown in FIG. 17. This novel second stage of the threestage power source is an unregulated inverter which includes anisolation feature and has a second DC output or second DC bus which isproportional to the DC input bus. The level relationship is fixed by theconstruction of the unregulated inverter. The unregulated second stageinverter has a switching network wherein the switches are operated at ahigh switching frequency greater than 18 kHz and preferably about 100kHz. The switching frequency of the switch network in the unregulatedinverter forming the second stage of the power source allows use ofsmall magnetic components. The isolated DC output of the unregulatedinverter is directed to a third stage of the power source. This thirdstage can be either a chopper or inverter which is regulated by awelding parameter, such as current, voltage or power of the weldingoperation. In the modification this third stage is preferably a chopper.The topography of the three stage power source has an input stage toproduce a first DC signal, a second unregulated DC to DC stage toprovide an isolated fixed DC voltage or DC bus that is used by the thirdstage of the power source for regulating the current used in the weldingoperation. Three examples of a three stage power source to which thepresent invention is directed are illustrated in FIGS. 1-3. Power sourcePS1 in FIG. 1 includes first stage I, second stage II, and third stageIII. In this embodiment, stage I includes an AC to DC converter 10 forconverting AC input signal 12 into a first DC bus 14. The input 12 is anone phase or three phase AC line supply with voltage that can varybetween 400-700 volts. Converter 10 is illustrated as an unregulateddevice which can be in the form of a rectifier and filter network toproduce DC bus 14 identified as (DC#1). Since the AC input signal is aline voltage, DC bus 14 is generally uniform in magnitude. Unregulatedinverter A is a DC to DC converter with an isolation transformer toconvert the DC bus 14 (DC#1) into a second DC bus or second DC output 20(DC#2). Output 20 forms the power input to stage III which is converter30. The DC voltage on line 20 is converted by converter 30 into acurrent suitable for welding at line B. A feedback control or regulationloop C senses a parameter in the welding operation and regulates thecurrent, voltage or power on line B by regulation of converter 30. Inpractice, converter 30 is a chopper, although use of an inverter is analternative. By having a three stage power source PS1 as shown in FIG.1, the switching network of the second stage has a frequency that isnormally higher than the switching frequency of converter 30.Furthermore, the DC voltage in line 20 (DC#2) is substantially less thanthe DC voltage from stage I on line 14 (DC#1). In practice, there is anisolation transformer in inverter A. The transformer has an input orprimary section or side with substantially more turns than the secondarysection or side used to create the voltage on line 20. This turn ratioin practice is 4:1 so that the voltage on line 20 is ¼ the voltage online 14.

The general topography of three stage power source is illustrated inFIG. 1; however, FIG. 2 illustrates an implementation wherein powersource PS2 has essentially the same stage II and stage III as powersource PS1; however, input stage I is an AC to DC converter 40 includinga rectifier followed by a regulated DC to DC converter. The convertedsignal is a DC signal in line 14 shown as a first DC bus (DC#1). Thevoltage on line 14 is regulated as indicated by feedback line 42 inaccordance with standard technology. Thus, in power source PS2 theoutput welding converter 30 is regulated by feedback loop C. The voltageon line 14 is regulated by feedback loop shown as line 42. Sinceconverter 40 is a power factor correcting converter it senses thevoltage waveform as represented by line 44. By using power source PS2,the first DC bus 14 is a fixed DC voltage with different one phase orthree phase voltages at input 12. Thus, output 20 is merely a conversionof the DC voltage on line 14. DC#2 is a fixed voltage with a leveldetermined by the isolation transformer and the fixed duty cycle of theswitching network in unregulated inverter A. This is an exemplaryimplementation of the power source employing three separate and distinctstages with stage II being an unregulated inverter for converting afixed first DC output or DC bus to a second fixed DC output or DC busused to drive a regulated welding converter, such as a chopper orinverter. As another alternative, stage I could be regulated by afeedback from the DC #2 bus in line 20. This is represented by thedashed line 46 in FIG. 2.

Power source PS3 in FIG. 3 is another implementation of the three stagepower source. The three stage power source of the present invention canhave the input converter 50 regulated by feedback loop 52 from thewelding current output B. With this use of a three stage power source,converter 50 is regulated by the welding output and not by the voltageon line 14 as in power source PS2. With regulation from welding outputB, converter 50 is both a power factor correcting stage and a weldingregulator.

As previously described, input stage I converts either a single phase ora three phase AC signal 12 into a fixed DC bus 14 (DC#1) for use by theunregulated inverter A constituting second stage II. The novel threestage power source generally employs a DC to DC converter in stage I toproduce the DC voltage indicated as line 14 in FIGS. 1-3. The DC to DCconverter of stage I can be selected to create the desired voltage online 14. Three of these converters are shown in FIGS. 4-6 wherein aninput rectifier 60 provides a DC voltage in lines 60 a, 60 b to a DC toDC converter which may be a boost converter 62, a buck converter 64 or abuck+boost converter 66, as shown in FIG. 4, FIG. 5 and FIG. 6,respectively. By using these converters, the DC to DC converter of stageI incorporates a power factor correcting chip, which chip allows thepower factor to be corrected thereby reducing the harmonic distortion atthe input of the power source. The use of a power factor correctinginput DC to DC converter is well known in the welding art and is used inmany prior art two stage topographies. Converters 62, 64 and 66preferably include a power factor correcting chip; however, this is notrequired. The main purpose of stage I is to provide a DC bus (DC#1) inline 14, which bus is indicated to be lines 14 a, 14 b in FIGS. 4-6 toproduce a fixed DC voltage (DC#2) in line 20 indicated by lines 20 a, 20b in the same figures. Power factor correction is not required to takeadvantage of the novel three stage topography. A non power factorcorrecting input stage is illustrated in FIG. 7 where the output lines60 a, 60 b of rectifier 60 are coupled by a large storage capacitor 68to produce a generally fixed voltage in lines 14 a, 14 b. Stage I inFIG. 7 does not incorporate a power factor correcting circuit or chip.However, the power source still involves three stages wherein the secondstage is unregulated isolated inverter A to produce a generally fixedvoltage on lines 20 a, 20 b. Another modification of input stage I isillustrated in FIG. 8 where a passive power factor correcting circuit 70is connected to a three phase AC input L1, L2 and L3 to produce agenerally fixed DC voltage across lines 14 a, 14 b, which linesconstitutes the DC bus 14 (DC#1) at the input of inverter A. Thedisclosures of modified stage I in FIGS. 4-8 are only representative innature and other input stages could be used with either single phase orthree phase input signal and with or without power factor correcting.

By providing low fixed voltage on output bus 20 illustrated as lines 20a, 20 b, the third stage of the novel three stage power source forwelding can be a chopper or other converter operated at a frequencygreater than 18 kHz. The switching frequencies of the unregulatedinverter and the regulated output converter may be different. Indeed,normally the switching frequency of the chopper is substantially lessthan the frequency of unregulated inverter A. Power source PS4 shown inFIG. 9 illustrates the use of the present invention wherein stage III isa standard regulated converter 100 of the type used for electric arcwelding. This converter is driven by fixed input DC bus 20 and isregulated by feedback from the welding operation 120 to provide currentsuitable for welding across output leads 102, 104. Leads 102 is apositive polarity lead and leads 104 is a negative polarity lead. Inaccordance with standard output technology for a two stage inverterbased power sources, leads 102, 104 are directed to a standard polarityswitch 110. This switch has a first position wherein lead 102 isdirected to the electrode of the welding operation 120 so the output ofpolarity switch 110 has a positive polarity on output line 110 a and anegative polarity on output line 110 b. This produces an electrodepositive DC welding process at weld operation 120. Reversal of polarityswitch network 110 can produce an electrode negative DC welding processat weld operation 120. Thus, a DC welding process with either DCnegative or DC positive can be performed according to the setting of thestandard polarity switch 110. In a like manner, polarity switch 110 canbe alternated between electrode negative and electrode positive toproduce an AC welding process at weld operation 120. This is standardtechnology wherein polarity switch 110 drives the DC output fromregulated converter 100 to produce either an AC welding process or a DCwelding process. This process is regulated and controlled by a feedbacksystem indicated as line or loop 122 directed to controller 130 forregulating converter 100 and for setting the polarity of switch 110 asindicated by lines 132, 134, respectively. By regulating the weldingoperation at stage III, the unregulated inverter at stage II can have arelatively higher switching frequency to reduce the component sizeswithin the second stage of the power source. The exemplary embodiment ofthe three stage power source employs waveform control technologypioneered by The Lincoln Electric Company of Cleveland, Ohio. This typeof control system is well known and is schematically illustrated in FIG.9A wherein control circuit 150 processes a waveform profile as a voltageon line 152 a is outputted from waveform generator 152. The waveformprofile is controlled by feedback loop 122 as schematically illustratedby error amplifier 154 having an output 156. Thus, the profile of thewaveform from generator 152 is controlled by the feedback loop 122 andproduces a signal in output line 156. This line is directed to anappropriate pulse width modulator circuit 160 operated at a highfrequency determined by the output of oscillator 162. This frequency isgreater than 18 kHz and is often higher than 40 kHz. The regulatedconverter 100 preferably operates under about 100 kHz. The output of thepulse width modulator, which is normally a digital circuit withincontroller 130, is shown as line 132 for controlling the waveform by wayof regulated converter 100. In accordance with standard practice, thewaveform of inverter 100 can have any profile, either AC or DC. Thisfeature is schematically illustrated as waveform 152 b, 152 c and 152 dat the right portion of FIG. 9A. Waveform 152 b is an AC waveform of thetype used in AC MIG welding where a higher negative electrode amperageis provided. A higher positive amperage is also common. In waveform 152c, the amperage for both electrode negative and electrode positive isessentially the same with the length of the negative electrode portionbeing greater. Of course, a process for AC welding can be adjusted toprovide balanced AC waveforms or unbalanced AC waveforms, either infavor of electrode negative or electrode positive. When polarity switch110 is set for either a DC negative or a DC positive welding operation,a pulse welding waveform, shown as waveform 152 d, is controlled bywaveform generator 152. Various other waveforms, both AC and DC, can becontrolled by controller 130 so the welding operation 120 can beadjusted to be AC, or DC. Furthermore, the welding operation can be TIG,MIG, submerged arc or otherwise. Any process can be performed by powersource PS4 or other power sources using the present invention. Theelectrode can be non-consumable or consumable, such as metal cored, fluxcored or solid wire. A shielding gas may or may not be used according tothe electrode being employed. A modification of power source PS4 toperform only DC welding is illustrated as power source PS5 in FIG. 10.In this power source, welding operation 120 performs only a DC weldingoperation so that feedback loop 122 is directed to controller 170 havingan output 172. Regulated converter 100 a is preferably a chopper toproduce a DC voltage across lines 102 a, 104 a. Controller 170 iscontrolled by waveform generator 152, as shown in FIG. 9A. The polarityon lines 102 a, 104 a is either electrode negative or electrode positiveaccording to the demand of the DC welding process performed at weldingoperation 120. Regulated converter 100 a is more simplified than thewelding output of power supply PS4 shown in FIG. 9. FIGS. 9 and 10,together with the control network or circuit 150 shown in FIG. 9A,illustrates the versatility of the novel three stage power source.

It is necessary to provide a voltage for operating the controllers forboth the regulated and unregulated switching networks used in these twotypes of power sources. FIG. 11 illustrates the architecture and schemeemployed to obtain control voltages to operate the various controllersof a three stage power source, such as power source PS6. The use of anoutput of a preregulator to provide the control voltage for theswitching controller of the preregulator and switching controller of thesecond stage of a two stage power source is well known and is disclosedin Moriguchi U.S. Pat. No. 5,926,381, incorporated by reference herein.An output chopper for performing a welding operation routinely obtainsthe controller control voltage from the input DC voltage to the chopper.These two well known technologies are incorporated in power source PS6.The three stage power source can be operated with controllers havingpower supplies derived from various locations in the power source. Beingmore specific, power source PS6 has a power supply 180 with an output182 and inputs 184, 186 from the first DC bus on leads 14 a, 14 b(DC#1). Power supply 180 includes a buck converter or flyback converter,not shown, to reduce the high voltage at the output of preregulator 40of FIG. 2 to a low voltage on line 182. This control voltage may bebetween 5 and 20 volts. Voltage on line 182 is directed to controller190 having an output lead 192 for performing the operation ofpreregulator 40 in accordance with standard technology. The preregulatorhas regulation feedback lines 42, 44 shown in FIGS. 2 and 3, but omittedin FIG. 11. Unregulated inverter A does not require a controller tomodulate the duty cycle or the fixed relationship between the input andoutput voltages. However, it does require a controller 194 that receivescontroller operating voltage in line 196 from power supply 180. Thisarrangement is similar to the concept disclosed in Moriguchi U.S. Pat.No. 5,926,381, except second stage controller 194 is not a regulatingcontroller as used in the two stage power source of the prior art. As analternative, power supply PS#3 is driven by one phase of input 12 togive an optional power supply voltage shown as dashed line 176.Regulated output converter 30 of stage III has a power supply 200labeled PS#2 with a controller voltage on line 202 determined by thevoltage on DC bus 20 (DC#2) illustrated as including leads 20 a, 20 b.Again, power supply 200 includes a buck converter or flyback converterto convert the DC bus at the output of unregulated converter A to alower voltage for use by controller 210 having an output 212. The signalon line 212 regulates the output of welding converter 30 in accordancewith the feedback signal on line C, as discussed with respect to powersources PS1, PS2 in FIGS. 1 and 2, respectively. DC bus 14 (DC#1) and DCbus 20 (DC#2) provides input to power supplies 180, 200 which are DC toDC converters to produce low level DC control voltage for controllers190, 194 and 210. As an alternative shown by dashed line 220, powersupply 180 labeled PS#2 can provide control voltage for controller 210.FIG. 11 has been disclosed to illustrate the versatility of using athree stage power source with controllers that can receive reducedsupply voltages from various fixed DC voltage levels indicated to bePS#1 and PS#2. Other arrangements could be employed for providing thecontroller voltage, such as a rectified connection to one phase of ACinput voltage 12 by a transformer in a manner illustrated as PS#3.

Power source PS7 in FIG. 12 is similar to power source PS6 withcomponents having the same identification numbers. The output stage IIIis a chopper 230 for directing a DC current between electrode E andworkpiece W. Current shunt S provides the feedback signal C tocontroller 210. High switching speed inverter 240 of stage II hascharacteristics so far described with the isolation provided bytransformer 250 having primary winding 252 and secondary winding 254.The primary side of DC to DC converter 240 is the switching networkdirecting an alternating current to primary winding 252. The rectifiedoutput from secondary 254 is the secondary section or side of converter240. Converter 240 employs a high switching speed inverter that has aduty cycle or phase shift set by controller 194. The switching frequencyis about 100 kHz in the practical version of this power source. The dutycycle remains the same during the welding operation by chopper 230;however, the duty cycle or phase shift of the inverter may be adjustedas indicated by “ADJ” circuit 260 having an output 262 for adjustingcontroller 194. The duty cycle is normally close to 100% so that theswitch pairs are conductive together their maximum times at the primaryside of inverter 240. However, to change the fixed relationship betweenthe first DC bus 14 and the second DC bus 20, circuit 260 can be used toadjust the duty cycle or phase shift. Thus, the unregulated, isolationinverter 240 is changed to have a different, but fixed duty cycle.However, the duty cycle normally is quite close to 100% so the switchpairs are operated essentially in unison. The duty cycle probably variesbetween 80-100% in normal applications of the three stage power source.In exemplary implementations of the power source, boost converter 62shown in FIG. 4 is used for a power factor correcting input stage I.This boost converter is operated in accordance with controller 190having a control voltage 182 as previously described. In accordance witha slight modification, supply 270 has a transformer connected by lines272, 274 across one phase of a single phase or three phase AC input 12.A rectifier and filter in power supply 270 produces a low controlvoltage in optimal dashed line 276 for use instead of the controlvoltage in line 182 if desired. These two alternatives do not affect theoperating characteristics of power source PS7. Other such modificationsof a three stage power source for electric arc welding can be obtainedfrom the previous description and well known technology in the weldingfield.

Input stage I normally includes a rectifier and a power factorcorrecting DC to DC converter as disclosed in FIGS. 4-8. These inputstages can be used for both three phase and single phase AC signals ofvarious magnitudes, represented as input 12. Certain aspects of an inputstage for three phase AC input power are disclosed with respect to thecircuits in FIGS. 13-16. Each of these circuits has a three phase inputand a DC bus output (DC#1) that is obtained with a low harmonicdistortion factor and a high power factor for the input stage. Thedisclosure in FIGS. 1-12 are generally applicable to the novel threestage power source; however, the particular stage I used is relevant toboth a two stage power source of the prior art or the novel three stagepower source. In FIG. 13, the input circuit 300 of stage I includes athree phase rectifier 302 with output leads 302 a, 302 b. Boost switch310 is in series with an inductor 312, diode 314 and a parallelcapacitor 316. An appropriate circuit 320 which is a standard powerfactor correcting chip has an input 322 to determine the input voltage,a regulation feedback line 322 a and an output 324 for operating theboost switch to cause the current in input 12 to be generally in phasewith the input voltage. This chip is a standard power factor correctingboost converter chip that can be used in the present invention and isalso used for a normal two stage power source. In a like manner, inputcircuit 330 shown in FIG. 14 has a three phase rectifier 302 with outputleads 302 a, 302 b as previously described. A boost circuit includinginductor 350, diodes 352, 354 and capacitors 356, 358 are used inconjunction with switches 340, 342 to provide coordination of thecurrent at the output of circuit 330 and input voltage 12. To accomplishthis objective, a standard chip 360 provides gating pulses in lines 362,364 in accordance with the sensed voltage in input 366 and feedbackregulation signals in lines 367, 368. This is standard technology toprovide power factor correction of the type that forms the input of atwo stage power source or the novel three stage power source. It hasbeen found that the active three phase circuits 300, 330 when operatedon a three phase input provide an input power factor of about 0.95. Thepower factor of a stage I when having a single phase AC input can becorrected upwardly to about 0.99. Since a three phase power source cangenerally be corrected only to a lower level, it has been found that apassive circuit for the input stage I of a two stage or three stagepower source is somewhat commensurate with the ability of an activepower factor correcting circuit. A standard passive circuit 400 is shownin FIG. 15, wherein each of the three phases is rectified by three phaserectifier 302 which directs DC current through output leads 302 a, 302 bto a filter circuit including inductor 412 and capacitor 414. It hasbeen found that a passive circuit such as shown in FIG. 15 can correctthe power factor of the three phase input to a level generally in therange of about 0.95. This is somewhat the same as the ability of anactive circuit for a three phase input circuit. A buck+boost inputcircuit 420 is shown in FIG. 16. Rectified current on lines 302 a, 302 bis first bucked by switch 422 using standard power factor correctingchip 430 having a line #32 having a voltage waveform signal from input12, that also steers chip 434 to operate boost switch 440. Switches 422,440 are operated in unison to control the input power factor using acircuit containing inductor 450, diode 452 and capacitor 454. Circuits300, 330, 400 and 420 are standard three phase passive power factorcorrecting circuits using standard technology and available switchescontrolled by the input voltage waveform and the current of DC#1. FIGS.13-16 are illustrative of certain modifications that can be made to thefirst stage of the three stage power source. Of course, there is othertechnology for improving the power factor and reducing the harmonicdistortion of both DC and AC signals of the type used to drive powersources of electric arc welders.

Unregulated inverter A of stage II can use various inverter circuits. Anexemplary circuit is illustrated in FIG. 17 wherein the inverter isdivided between a primary section or side defined by the input toprimary winding 252 of isolating transformer 250 and a secondary sectionor side defined by output of secondary winding 254. Referring first tothe primary section or side of inverter A, full bridge circuit 500 isemployed wherein paired switches SW1-SW2 and SW3-SW4 are acrosscapacitor 548 are connected by leads 502, 504. The switches areenergized in alternate sequence by gating pulses on lines 510, 512, 514,and 516, respectively. Controller 194 outputs gating pulses in lines510-516 and an adjusted duty cycle determined by the logic on line 262from circuit 260 as previously discussed. The duty cycle is controlledby changing the phase shift of lines 510 and 512 and lines 514 and 516.Circuit 260 adjusts the duty cycle or phase shift of the pairedswitches. This adjustment is fixed during the operation of inverter A.In practice, circuit 500 has about 50% duty cycle or phase shift, whereeach pair of switches has maximum periods of conduction. Preferably theduty cycle is about 100% or 80-100%. Controller 194 has a controlvoltage from an appropriate supply indicated by line 196, as alsopreviously described. In operation of circuit 500, an alternatingcurrent is directed through primary winding 252. This current has anultra high frequency normally at least about 100 kHz so the componentscan be reduced in size, weight and cost. The high switching frequency isnot dictated by the welding operation, but is selected for efficiency ofunregulated stage A of the three stage power source. The secondarysection or side of inverter A is a rectifier 520 having synchronousrectifier devices 522, 524. Synchronous rectifier devices are well knownin the general electrical engineering art and are discussed in BoylanU.S. Pat. No. 6,618,274 incorporated by reference herein. These devicesare gated by signals on lines 526, 528 created at the opposite ends ofsecondary winding 254 in accordance with standard technology. Leads 530,532, and 534 form the output leads of rectifier 520 to create a DCvoltage (DC#2) across leads 20 a, 20 b. The current is smooth by a choke544 and is across capacitor 546, in accordance with standard weldingtechnology. Inverter A is unregulated which means that it is notadjusted by a real time feedback signal from the welding operation. Itmerely converts DC bus 12 (DC#1) to DC bus 20 (DC#2). This conversionallows a substantial reduction in the voltage directed to the regulatedthird stage of the power source using inverter A. The reduction involtage is primarily determined by the turns ratio of transformer 250,which ratio, in an exemplary embodiment, is about 4:1. Thus, the fixedvoltage on output bus 20 is about ¼ the fixed voltage on output bus 12of the first stage. Several advantages of an unregulated stage arecontained in an article entitled The incredible Shrinking (Unregulated)Power Supply by Dr. Ray Ridley incorporated by reference herein asbackground information. A basic advantage is the ability to increase thefrequency to above 100 kHz to reduce the size and cost of the inverterstage.

Various circuits can be used for the unregulated inverter A constitutingnovel stage II of the invention. The particular type of inverter is notcontrolling. Several inverters have been used. Some are illustrated inFIGS. 18-21. In FIG. 18, inverter A is shown as using a full bridgecircuit 600 on the primary side of transformer 250. A switch and diodeparallel circuit 602, 604, 606 and 608 are operated in accordance withthe standard phase shift full bridge technology, as explained withrespect to the inverter A version shown in FIG. 17. A modification ofthe internal workings for inverter A is illustrated in FIG. 19 utilizinga cascaded bridge with series mounted switch circuits 610, 612 and 614,616. These switch circuits are operated similar to a half bridge andinclude input capacitors 548 a, 548 b providing energy for the switchingcircuits which in parallel is capacitor 620 and is in series with diode622, 624. The two switch circuits are in series so there is a reducedvoltage across individual switches when a phase shift control techniquesimilar to the technique for the full bridge inverter of FIG. 17 isused. This type of inverter switching network is illustrated inCanales-Abarca U.S. Pat. No. 6,349,044 incorporated by reference hereinshowing an inverter using a cascaded bridge, sometimes referred to as athree level inverter. A double forward inverter is shown in FIG. 20wherein switches 630, 632 provide a pulse in section 252 a of theprimary winding for transformer 250 a. In a like manner, switches 634,636 are operated in unison to provide an opposite polarity pulse inprimary section 252 b. The alternating pulse produces an AC at theprimary winding of transformer 250 a to produce an isolated DC output insecondary winding 254. A standard half bridge circuit is shown as thearchitecture of inverter A in FIG. 21. This half bridge includesswitches 640, 642 alternately switched to produce an AC in primarywinding 252 of transformer 250. These and other switching circuits canbe used to provide an AC signal in the primary winding of transformer250 so that the secondary isolated AC signal is rectified and outputtedon leads 20 a, 20 b as DC#2. The mere description of certainrepresentative standard switching networks is not considered to beexhaustive, but just illustrative. Control of the welding current is notperformed in the second stage. In this stage, a DC bus having a highvoltage is converted to a fixed DC bus (DC#2) having a low voltage forthe purposes of driving a third stage, which third stage is a regulatedstage to provide a current suitable for electric arc welding. Electricarc welding incorporates and is intended to include other weldingrelated applications, such as the concept of plasma cutting. The variouscircuits used in the three stages can be combined to construct variousarchitectures for the basic topography which is a three stage powersource.

Further exemplary embodiments, as generally represented in FIG. 11, canbe formed into a modularized construction, as illustrated in FIG. 22.Power source 700 includes a first module 702 forming a fixed assembledframe on a single base. This module includes the first input stage 62and the isolation or second stage, in the form of unregulated inverterA. As in FIG. 11, two controllers, shown in two stages such ascontroller 190 and controller 194, direct control signals on lines 192,198 into the two separate stages of module 702. The output of firstmodule 702 are lines 20 a, 20 b (DC #2). This output voltage is directedto a separate, second module or frame 704. The second frame supports theoutput third stage of the controller, illustrated as chopper 30 in FIGS.11 and 22. Weld controller 210 controls the output of chopper 30 througha signal on input line 212. This signal is generated by a pulse widthmodulator under the direction of a wave shaper or waveform generator incontroller 210. Power to controller 210 is provided by the second DC busby lines 204, 206. A feedback current signal from shunt S is received bycurrent sensor circuit 706 that creates a signal on line 706 a,representing the output or weld current of the welding operation. In alike manner, voltage sensor circuit 708 detects the voltage across thearc of the welding operation and provides a signal on line 708 arepresenting the welding voltage. These two signals are directed intothe feedback circuit of controller 210 to determine the chopper inputsignal on line 212. By mounting the output third stage on separatemodule 704, this module can be changed to modify the power source forperforming different welding operations. Furthermore different chopperscan be used as the third stage of power source 700. The power source isnot mounted on a single module, but on an input module 702 and aseparate last stage power module 704. Other advantages of this novelmodularized construction will be discussed in the implementations of theinvention shown in FIGS. 28 and 29.

FIGS. 23 and 24 show two output circuits for use on module 704. In FIG.23, chopper 710 is mounted on replaceable module 704 to be operated bycontroller 210 with a signal on line 212. Chopper 710 includes powerswitch 712 controlled by high frequency signals on line 212. The signalis created by a pulse width modulator in controller 210. Power switch712 directs current from input leads 20 a, 20 b through choke 714 toperform a welding operation between electrode E and workpiece W. Filtercapacitor 718 is connected across the DC bus or leads 20 a, 20 b forcontrolling the voltage signal to chopper 710. This output chopper isreleasably connected to the input leads 20 a, 20 b to the three stagepower source 700 in FIG. 22. Thus, the three stage power source has anoutput chopper. An output chopper is an exemplary embodiment of theinvention; however, the separate module 704 can include another outputcircuit, such as the STT circuit 730 shown in FIG. 24. This STT circuitincludes power switch 732 for directing current pulses through choke 734to the welding operation between electrode E and workpiece W. The signalon line 212 forms an STT pulse profile at the welding operation. The STTwaveform or profile is unique to The Lincoln Electric Company and isdescribed in several patents, such as Parks U.S. Pat. No. 4,866,247incorporated by reference herein. STT circuit 730 includes premonitionswitch 740 having an input 740 a activated when the short circuit metaltransfer is approaching a rupture of the metal neck between theelectrode and workpiece. Just before the rupture occurs, switch 740 isclosed to increase the current flow for the purposes of separating theshort circuited molten metal. When the switch is opened, resistor 742 isconnected in the series circuit including choke 734 and electrode E.Capacitor 744 controls the voltage across switch 740 when the switch isopened to transfer current flow to resistor 742. Diode 746 preventscurrent flow in the reverse direction in resistor 734 to dischargecapacitor 744. Input filter capacitor 738 is connected between the DCbus formed by leads 20 a, 20 b. If an STT welding operation is to beperformed by power source 700, module 730 shown in FIG. 24 is used toreplace chopper module 710 shown in FIG. 23. These figures illustratethe interchangeability of the output circuit on module 704 to performdifferent welding operations.

Another aspect of the present invention is a novel output chopper foruse on module 704. This new output chopper is shown in FIG. 25, whereinchopper 750 has a dual mode of operation. It has two separate anddistinct polarity paths. The first path include polarity switch 760operated by control pulses on line 762. In series with polarity switch760 and choke 770 is modulating switch 764 receiving gating pulses online 766 and having free wheeling diode 788. Operation of polarityswitch 760 and modulating switch 764 causes current flow across the gapbetween electrode E and workpiece W in a first polarity direction. Asecond path creates a current flow across the welding arc in theopposite polarity and includes polarity switch 780 receiving gatingpulses on line 782. Corresponding modulating switch 784 has a gatingsignal line 786 and free wheeling diode 768. The choke 790 in the secondpolarity path corresponds to choke 770 in the first polarity path.Switch signal control device 800 creates signals in line 762 and line766 for operating the first polarity path. In a like manner, signals inline 782 and line 786 causes a current flow in the opposite polaritypath. Control 800 has a frequency determined by oscillator 802 andinvolves a pulse width modulator in the controller in digital format.Device 804 selects the mode of operation. This device allows one of thepolarity paths to be operated to merely provide a standard choppercircuit in either the positive or negative direction. By alternating thepulses to the two polarity paths, an AC output signal is created. Themodulating switches 764, 784 are essentially the power switches of thetwo chopper modes in chopper 750. This is a chopper circuit to providean AC output. A separate and distinct polarity switch as shown in FIG. 9is not required. Dual mode chopper 750 is novel for electric arc weldingand essentially employs a chopper that can be reversed in polarity andcan be operated in an AC mode. Thus, the welding operation betweenelectrode E and workpiece W can be shifted between different modes whileusing the same circuit and with the advantage of a chopper concept.Chopper 750, when operated in the AC mode, is a substantial improvementover the prior art AC welding power source, illustrated in FIG. 26. Thisprior unit is a full bridge output circuit having separate polaritypaths with a double forward bias voltage drop. There is no chopperconcept. Voltage 810 is driven by inverter 812 used to convert DC link820, 822 to output DC bus 830, 832. This DC bus drives the full bridgethrough choke 834. Bridge 810 has switches 840, 842 operated by leads aand switches 850, 852 driven by leads b. The signals to the switches arecreated by controller 860 to alternate between the two sets of powerswitches, each of which has an anti-parallel diode 840 a, 842 a, 850 aand 852 a, respectively. The dual mode chopper shown in FIG. 25 canprovide not only AC operation, but also output modulating. This is asubstantial improvement over bridge 810 and does not need an inputinverter 812. Any of the output modules disclosed in FIGS. 23, 24 and 25can be used in the three stage power source 700, as schematicallyillustrated in FIG. 22. Module 704 with one of these circuits is used asthe output stage connected to two stage input module 702.

In accordance with another aspect of the present invention, the outputchopper of module 704 is provided with a soft switching circuit 900, asbest shown in FIG. 27. Chopper 710 of FIG. 23 has power switch 712driven by pulse width modulator 880 at a frequency controlled byoscillator 882. The output 880 a of pulse width modulator 880 iscontrolled by input 880 b under the control by comparator 884 thatcompares a command signal from a wave shaper or waveform generator online 886 with the feedback circuit signal on line 706 a. This is thenormal operation for a chopper. Soft switching circuit 900 is a commonlyused soft switching circuit. The circuit includes an inductor 902 forcontrolling current across the power switch and diode D4. Capacitor 906controls the voltage across the power switch during the switchingoperations. Capacitors 904 and 906 are connected as shown in FIG. 27using diodes D1, D2, D3 and D4. These capacitors control the voltageacross switch 712. Inductor 902 controls the current through diode D4.Thus switch 712 and diode D4 are soft switched in both the current andvoltage during switching operations. This circuit is shown in theUniversity of California article entitled Properties and Synthesis ofPassive, Loseless Soft-Switching PWM Converters. This May 1997 articleis incorporated by reference herein to explain further the operation ofthe commonly used circuit 900. In essence, chopper 710 has a powerswitch with a soft switching circuit to control both the current andvoltage during turn-on and turn-off sequences of the power switch. Thesame type of soft switching circuit is employed for power switches 760,780 of dual mode chopper 750. In other words, the output chopper onmodule 74 is provided with a soft switching circuit, which softswitching circuit controls both voltage and current at the appropriatetime during the switching operations.

FIGS. 28 and 29 illustrate two advantages of modularizing power source700. In FIG. 28, module 704 is provided with output power stage 920,which may be a DC chopper as shown in FIG. 23, an AC chopper as shown inFIG. 25 or an STT circuit shown in FIG. 24. By using the invention,different modules 704 can be connected to input module 702 for buildingdifferent types of power sources, while maintaining the novel threestage topography. Controller 922 combines the functions of controllers190, 194 shown in FIGS. 11 and 22 and receives control voltage from line924. Turning now to FIG. 29, a second advantage of using the modularizedthree stage power source of the invention is illustrated. Two separateinput modules 702 a, 702 b are connected in parallel by interconnectingthe output leads 20 a, 20 b from each of the two input modules. Thus,chopper 30 has an input level which is higher than available from asingle module 702. Of course, more than two input modules could beemployed to create a substantial amount of welding current at the inputof chopper 30. In FIG. 29, power source 700 a includes the two inputmodules 702 a, 702 b which are controlled in unison by controller 930through output lines 192 a, 198 a and output lines 192 b and 198 b.Control voltage is provided by the DC bus in modules 702 a, 702 b bylines 932, 934, respectively. Thus, by using a modularized three stagepower source of the present invention, the output stage can beselectively changed or the input stage can be parallel. Paralleling ofsmaller modules reduces the number of modules needed from a wide rangeof power levels. Two advantages of modularization are illustrated inFIGS. 28 and 29. Other advantages are apparent to create versatilitywhile maintaining the advantage of the novel three stage power sourceshown in FIGS. 1-21.

The power sources disclosed in FIGS. 1-21 and the dual mode choppershown in FIG. 25 can perform a large number of welding processes. FIGS.30-41 illustrate the combination of such power sources with thesewelding processes. In FIG. 30, submerged arc MIG welding process 1000employs novel three stage power source 1010 having output leads 1012,1014. Lead 1014 can be a ground lead in accordance with standardtechnology. The submerged arc welding process involves electrode Emovable along workpiece WP and surrounded, at the workpiece, by a massof granulated flux material 1020. As electrode E moves with respect toworkpiece WP, the electrode plows through granular flux 1020 to protectthe welding arc and molten metal puddle prior to solidification. Inaccordance with an aspect of the invention the welding process isperformed by the three stage power source disclosed in FIGS. 1-21. Inone embodiment of the invention, electrode E is a flux cored electrode,as shown in FIG. 31 wherein the electrode is a wire including an outermetal sheath 1030 surrounding an internal core 1032 containing flux. Aflux cored electrode also includes granular material for alloying withthe steel of sheath 1030. The inclusion of alloy agents does not changethe definition of the electrode as being a “flux cored” electrode. Ifthere is no flux, the electrode can still be a “cored” electrode withmetal alloying material in granular form surrounded by sheath 1030. Theseveral welding processes disclosed herein can employ a solid wire, ametal cored electrode or a flux cored electrode, the latter beingschematically illustrated in FIG. 31.

In accordance with another aspect of the invention, the three stagepower source of FIGS. 1-21 is used in combination with tandem weldingprocess 1050, as illustrated in FIG. 31. This process uses three stagepower source 1060 having output leads 1062, 1064. A welding signal isdirected to electrode E′ movable in direction D along workpiece WP. Thesecond electrode E2 receives a welding signal from three stage powersource 180 having output leads 1082, 1084. The output leads of bothpower sources are connected to workpiece W1 by lead 1086. By movingelectrodes E1 and E2 along workpiece WP in direction D, a tandem weldingprocess is performed. This process is illustrated as being a submergedarc process using granular flux 1090. The MIG tandem process of FIG. 32need not be the submerged arc process and can merely use a flux coredelectrode, as shown in FIG. 31. When using the granular flux of asubmerged arc welding process, the electrodes are normally solid metalor metal cored.

The three stage power source of the present invention is combined withany welding process, such as TIG welding process 1100 shown in FIG. 33.Power source 1110 has output leads 1112, 1114 between electrode E andworkpiece WIP. The TIG welding process utilizes a tungsten electrode E,which electrode is not consumed during welding. To provide additionalmetal for the TIG welding process, filler metal rod F can be used. Asimilar combination of the three stage power source for generic MIGwelding process 1120 is illustrated in FIG. 34. Power source 1122 hasoutput leads 1124, 1126. Electrode E is a welding wire, flux cored orotherwise stored in a supply, illustrated as spool 1130. Consequently,welding wire W is moved through contact tip 1132 into the weldingprocess at workpiece WP. In accordance with standard MIG technology,lead 1124 is connected to contact tip 1132 for directing a weldingsignal to electrode E. This generic MIG welding process uses, incombination, the three stage power source disclosed in FIGS. 1-21.

The various welding output signals shown in FIGS. 35 and 36 are createdby either the novel three stage power source disclosed in FIGS. 1-21 orthe dual mode chopper illustrated in FIG. 25. In FIG. 35, AC weldingsignal 1200 includes positive portion 1202 and negative portion 1204.These portions are created by a series of closely spaced current pulses1210 created by waveform technology, where the magnitude of each pulseis determined by a pulse width modulator under the control of a waveshaper or waveform generator. This is in accordance with standardtechnology pioneered by The Lincoln Electric Company of Cleveland, Ohio.The AC welding signal of FIG. 35 can be replaced by DC welding signal1250, as shown in FIG. 36. Peak current 1252 can be a fixed value,either positive polarity or negative polarity. In the illustratedembodiment, welding signal 1250 is a pulse signal, wherein peak level1252 is preceded by ramp up portion 1254 and followed by ramp downportion 1256. This provides a pulse above background level 1258. Inaccordance with an exemplary embodiment of the invention, the waveformis produced by a series of individual current pulses 1260 created by apulse width modulator under the control of wave shaper or waveformgenerator.

The process and power source combinations illustrated in FIGS. 30-36 arepreferably performed by the novel dual mode chopper output stage asillustrated in FIG. 25. This concept is illustrated in FIGS. 37 and 38.In FIG. 37, MIG welding process 1300, which can be a submerged arcprocess by using granular flux, is illustrated as being combined withthree stage power source 1310 having an input two stage module 1312directing the output signal from the unregulated isolation DC to DCconverter to dual mode chopper 1314. The DC signal driving chopper 1314is in line 1316. The output welding signal on lead 1320 is a signal suchas shown in FIGS. 35 and 36. The welding signal is connected to contacttip 1132 for the MIG welding process 1300. TIG welding process 1350combined with power source 1310 is illustrated in FIG. 38. Thepreviously used numbers for the various components are used in FIG. 38.A welding signal as shown in FIGS. 35 and 36 is directed to tungstenelectrode E by output lead 1320. Filler metal rod F is used to provideadditional metal during the DC TIG welding process. Generally thisfiller metal is not employed for AC TIG welding, although it isavailable. Generic MIG welding process 1300 and generic TIG weldingprocess 1350, as illustrated in FIGS. 37, 38, respectively, are novelcombinations using dual mode chopper 710 disclosed in FIG. 25.

Dual mode chopper 750, as shown in FIG. 25, can be driven by a DC signalfrom various isolated input power sources to perform the combinedwelding processes. Use of a generic DC driving signal is illustrated inFIGS. 39-41, wherein like numbers as previously used correspond to thesame or like components. A MIG welding process 1400 is illustrated inFIG. 39, wherein generic DC input 1410 is converted by dual mode chopper1314 to create an AC or DC welding signal at contact tip 1132. The MIGwelding process 1400 of FIG. 39 is converted to a submerged arc MIGwelding process 1420 in FIG. 40. This conversion is accomplished byadding granular flux material 1422 around electrode E to protect the arcand molten metal puddle of the welding process. A dual mode chopper witha generic input DC driving signal 1410 is combined with a power sourceto provide TIG welding process 1430, illustrated in FIG. 41. The AC orDC welding signal on lead 1320 is used by tungsten electrode E for TIGwelding at workpiece WP.

As illustrated in FIGS. 30-41, the three stage power source shown inFIGS. 1-21 and the dual mode chopper as disclosed in FIG. 25 arecombined with certain welding processes to create novel methods, whichnovel methods form another aspect of the present invention. The methodsillustrated in FIGS. 30-41 disclose the invention of combining weldingprocesses with the novel power sources of the present invention.

Turning now to FIG. 42, an welding system 2000 is shown. As is typicalthe welding system 2000 contains a power supply 2010 coupled to a wirefeeder 2020. The power supply 2010 outputs a welding current, which isdirected to the wire feeder 2020 so that the wire feeder can pass thecurrent on to the electrode E for welding the workpiece W. A wirefeeding cable 2021 delivers the electrode E to a contact tip, whichimparts the welding current into the electrode E. Further, a power cable2011 delivers current from the power supply 2010 to the wire feeder2020, and a ground cable 2013 couples the power supply 2010 to theworkpiece W to provide a ground path. Additionally, sense leads 2015 and2017 are often used to sense a voltage and/or a current of the weldingoperation to allow for proper control of the welding operation. Also,although not shown, often a control cable couples the wire feeder 2020and the power supply 2010 so that these components can communicate witheach other. In some applications the control cable is made a part of thepower cable 2011, to minimize the number of cables connecting thecomponents. The power supply 2010 can be constructed in accordance withany power supply described herein, or any other known power supplytopology. Thus, FIG. 42 represents a generally typical welding systemand its detailed operation need not be described in detail herein. FIG.43 is representative of a welding power source 700 which is enclosed ina single housing structure 2040 consistent with common power sourcepractices. The topology shown in this figure is consistent with thatshown in FIG. 22 and its operation and structure will not be repeated.

However, it is noted that in some applications the wire feeder 2020 ispositioned a significant distance from the power supply 2010, thusrequiring the cables 2011 and 2013 to be quite long. This often occurswhen the welding operation is not conducive to having the power supply2010 close to the welding operation, but the wire feeder 2020 ispositioned close by to ensure proper wire feeding. In such applicationsthe sense leads 2015 and 2017 can also be very long. It is in theseapplications that issues can develop with a welding system.Specifically, long cables and sense leads are expensive and can breakfrom time to time. Further, these long cables can greatly increase theoverall system inductance during a welding operation. This increase ininductance can be a detriment to the welding operation because it canadversely affect the overall responsiveness of the welding power supply2010. This is particularly problematic in pulse welding operations.Further, cables 2011 and 2013 that have been coiled can also undesirablyincrease the system inductance. Therefore, it is desirable to reduce theoverall system inductance as much as possible. As explained below,embodiments of the present invention achieve this goal.

FIG. 44 depicts an exemplary embodiment of a welding system 3000 of thepresent invention. The depicted system 3000 comprises a power sourcecomponent and a wire feeding and power conversion component 3200,separated by power source cables 3110. As shown, each of the components3100 and 3200 have separate housings are when used are positioned remotefrom each other. That is, as shown in FIG. 42, the wire feeding/powerconversion module 3200 would be positioned nearer the welding operation,while the power source component 3100 would be positioned near the wherethe input power is provided. The power source component contains a powersource module 3700 and has a separate and distinct housing structure3101 from the wire feeding/power conversion component 3200. The powersource component 3100 comprises a power source module 3700 whichoperates consistent with how similar components were discussed above.For example, the module 3700 converts either a utility or generatorinput power into a stable, usable power which is transmitted via lines3110 to the wire feeder/power conversion component 3200. For example,the power source component 3100 can create a stable DC bus (similar tothat described previously in relation to FIGS. 1 through 41) which isthen used by the component 3200 to output a welding signal.

As shown in FIG. 44, the wire feeder/power conversion component 3200comprises a power conversion module 3704 and a wire feeder module 3210.The power conversion module 3704 operates similar to the modules 704discussed previously. That is, the power conversion module 3704 receivesthe power from the bus 3110 and converts the power to a desired weldingsignal. That is, the power from the power source component 3100 is notsuitable for welding in any way, and it is only after it is converted bythe module 3704 that the power can be used for welding. Stateddifferently, in exemplary embodiments of the present invention thewelding signal (i.e., the current signal sent to the contact tip 2023that is actually used for welding) is generated, controlled and modifiedwithin the separate and distinct wire feeder/power conversion component3200. As shown, the weld controller 210 is actually within component3200 along with the wire feeder electronics and control 3210. However,the wire feeder/power conversion component 3200 does not contain thecircuitry that is needed to convert the input power (at L1, L2 and L3)to usable energy for the module 3704. As shown, exemplary embodiments ofthe present invention, need two separate and distinct components, withseparate and distinct housings to form the system 3000 as shown.

Further, as stated above, the component 3200 also contains all of theneeded wire feeder electronics and control circuitry 3210 which areneeded to perform the desired wire feeding functions. The wire feederelectronics and control 3210 can be made consistent with known wirefeeder mechanisms, and the wire feeder can also receive power from thebus 3110 to power its components and operations. In fact, the weldcontroller 210 can also control the operation of the wire feedingaspects of the component 3200. As shown, in exemplary embodiments thewire feeder electronics and control circuitry 3210 is coupled to a wirefeeding motor 3213, which is mechanically coupled to a pulley structure3215. The pulley structure 3215 is used to push and/or pull theelectrode E to a welding operation. Because the operation and structureof wire feeding devices are known, no detailed discussion of theiroperation will be provided herein.

Because of the above construction, the system 3000 provides asignificant performance improvement over welding systems where thewelding power supply (which produces and provides the welding currentsignal) is separate from a traditional wire feeding mechanism (see FIG.42). That is, in embodiments of the present invention, the generationand manipulation of the welding current signal is occurring much closerto the welding operation. This significantly reduces the overallinductance of the welding system, by taking the cables 3110 out of thewelding current circuit. Moreover, embodiments of the present inventionprovide improved sensing and thus control over the welding process. Thisis particularly beneficial in pulse welding operations. Moreover, acontrol cable between the welding power supply and the wire feeder is nolonger needed. In fact, in exemplary embodiments of the presentinvention sense leads are completely eliminated. Specifically, becauseof the proximity of the generation of the welding signal to the weldingoperation, accurate sensing of the welding signal can be achieved by thepower conversion module 3704. Thus, embodiments of the present inventioneliminate the need for separate sense leads 2015 and 2017 between thewelding power supply and the welding operation. This can greatly improvethe responsiveness and performance of the welding operation.

Further, although not shown in FIG. 44, embodiments of the presentinvention also place a welding user interface in the wire feeder/powerconversion component 3200 such that the user can read and enter weldinginformation directly on the wire feeder 3200. This makes the operationof the system 3000 easier as it puts the user interface closer to thewelding operation. Thus, embodiments of the present invention cangreatly reduce the complexity of a welding system, while at the sametime significantly improving its responsiveness and performance. This isparticularly the case when using pulse-based welding waveforms whichrequire rapid reaction and response by the welding system.

An exemplary system is shown in FIG. 46 where it is shown that powerconversion/wire feeder component 3200 is positioned close to the weldingoperation. The component receives its steady state power from the powersource component 3100 and there is no connection between the powersource component and the work piece. Further, as shown in thisembodiment, there are no separate sense leads from either the components3100 or 3200 to the workpiece or welding operation. Instead the powerconversion/wire feeder 3200 uses the sensed current and voltage from thecables 2021 and 3220 to control the welding operation. There is noseparate feedback from the welding arc.

As explained above, with exemplary embodiments of the present invention,the power source component 3100 and power conversion/wire feedercomponent 3200 are separate and distinct components which have their ownindividual and separate housings. With embodiments of the presentinvention, these components can be placed apart from each other by verylarge distances, whereas with traditional welding systems there exists amaximum effective distance between the welding power supply and the wirefeeder. For example, traditional systems should not have more than 100feet in between the power supply and the wire feeder. However, withembodiments of the present invention, that distance can be greatlyexceeded without affecting the performance of the welding operation inany way. In fact, the components 3100 and 3200 can be separated fromeach other by a distance in the range of 100 to 500 feet. In otherexemplary embodiments the distance is in the range of 250 to 500 feet.

FIG. 45 depicts another exemplary embodiment of the present invention,where the system 4000 contains a power source component 4100 and a powerconversion/wire feeder component 4200 which are separated by cables4110, which can carry a DC bus as discussed previously. The topology ofthe welding components of the system 4000 are similar to that shown anddiscussed in FIG. 11, discussed above. Because the overall operation ofthe components is discussed relative to that Figure, that discussionwill not be repeated herein. However, the system 4000 is similar to thesystem 3000 in that the components each have their separate housings4101 and 4201, respectively. Also, as shown the component 4200 alsocontains the wire feeder electronics and control system and components4210. Further, as shown, control power for the controller 210 can beprovided from the power supply 180 as shown. This control power can beprovided by a separate cable and can be coupled to one of the bus cables4110.

It should be noted that embodiments of the present invention are notlimited to using the exemplary three-stage topology described herein,but can also be used with two-stage, or other welding power supplytopologies. Further, embodiments are not limited to using inverter-typepower supplies. However, in embodiments of the present invention, thesignal on the lines 4110 is not a welding signal, and the component 4200is incapable converting, smoothing, etc. the utility or generator inputpower to a signal state that can be used by the power conversion module3704 to create a welding signal.

Further, the power conversion module 3704 can contain any type ofwelding output structure as desired for a welding operation. That is,the module 3704 can utilize a chopper structure, a regulated converterstructure, a STT-type output circuit structure, or any other desiredwelding output stage. It is further noted that, although not shownexpressly in FIG. 45, the motor 3213 and pulley structure 3215 from FIG.44 which is used to feed the electrode E can also be similarly presentin the wire feeder component 4200. Again, these systems and componentsare generally known and need not be discussed in detail herein.

Additionally, as shown, the welding output controller 210 is alsoenclosed within the same housing 3201/4201 as the power conversion/wirefeeding components. Again, this optimizes performance. As generallyexplained previously, the controller 210 controls the welding operationto ensure that the desired welding output is provided. The controller210 can be any type computer controlled system, using digital electroniccircuitry, or in computer hardware, firmware, software, or incombinations of them. The implementation can be as a computer programproduct, i.e., a computer program tangibly embodied in an informationcarrier (e.g., a CPS). An information carrier can be a machine-readablestorage device or in a propagated signal, for execution by, or tocontrol the operation of, data processing apparatus (e.g., aprogrammable processor, a computer, or multiple computers).

A computer program (e.g., a computer program system) can be written inany form of programming language, including compiled or interpretedlanguages, and it can be deployed in any form, including as astand-alone program or as a module, component, subroutine, or other unitsuitable for use in a computing environment. A computer program can bedeployed to be executed on one computer or on multiple computers at onesite or distributed across multiple sites and interconnected by acommunication network.

Method steps can be performed by one or more programmable processorsexecuting a computer program to perform functions of the invention byoperating on input data and generating output. Method steps can also beperformed by, and apparatus can be implemented as, special purpose logiccircuitry, e.g., an FPGA (field programmable gate array) or an ASIC(application specific integrated circuit). Modules can refer to portionsof the computer program and/or the processor/special circuitry thatimplements that functionality.

Processors suitable for the execution of a computer program include, byway of example, both general and special purpose microprocessors, andany one or more processors of any kind of digital computer. Generally, aprocessor will receive instructions and data from a read-only memory ora random access memory or both. The essential elements of a computer area processor for executing instructions and one or more memory devicesfor storing instructions and data. Generally, a computer will alsoinclude, or be operatively coupled to receive data from or transfer datato, or both, one or more mass storage devices for storing data, (e.g.,magnetic, magneto-optical disks, or optical disks). Data transmissionand instructions can also occur over a communications network.Information carriers suitable for embodying computer programinstructions and data include all forms of non-volatile memory,including by way of example semiconductor memory devices, e.g., EPROM,EEPROM, and flash memory devices; magnetic disks, e.g., internal harddisks or removable disks; magneto-optical disks; and CD-ROM and DVD-ROMdisks. The processor and the memory can be supplemented by, orincorporated in special purpose logic circuitry.

To provide for interaction with a user, the above described techniquescan be implemented on a CNC or computer having a display device, e.g., aCRT (cathode ray tube) or LCD (liquid crystal display) monitor, fordisplaying information to the user and a keyboard and a pointing device,e.g., a mouse or a trackball, by which the user can provide input to thecomputer (e.g., interact with a user interface element). Other kinds ofdevices can be used to provide for interaction with a user as well; forexample, feedback provided to the user can be any form of sensoryfeedback, e.g., visual feedback, auditory feedback, or tactile feedback;and input from the user can be received in any form, including acoustic,speech, or tactile input.

The above described techniques can be implemented in a distributedcomputing system that includes a back-end component, e.g., as a dataserver, and/or a middleware component, e.g., an application server,and/or a front-end component, e.g., a client computer having a graphicaluser interface and/or a Web browser through which a user can interactwith an example implementation, or any combination of such back-end,middleware, or front-end components. The components of the system can beinterconnected by any form or medium of digital data communication,e.g., a communication network. Examples of communication networksinclude a local area network (“LAN”) and a wide area network (“WAN”),e.g., the Internet, and include both wired and wireless networks.

Comprise, include, and/or plural forms of each are open ended andinclude the listed parts and can include additional parts that are notlisted. And/or is open ended and includes one or more of the listedparts and combinations of the listed parts.

While the invention has been particularly shown and described withreference to specific illustrative embodiments, it should be understoodthat various changes in form and detail may be made without departingfrom the spirit and scope of the invention.

We claim:
 1. A power supply system for an electric arc welding process,said power supply system comprising: a first power supply componentcomprising: an input stage having an AC input and a first fixed DCoutput signal; a second stage in the form of an unregulated DC to DCconverter, unregulated by a feedback signal from the electric arcwelding process, having an input connected to said first fixed DC outputsignal, a network of switches switched at a high frequency with a givenduty cycle to convert said input into a first internal AC signal, anisolation transformer with a primary winding driven by said firstinternal AC signal and a secondary winding for creating a secondinternal AC signal; and a smoothing choke and a rectifier to convertsaid second internal AC signal into a second fixed DC output signal ofsaid second stage with a magnitude related to said duty cycle of saidswitches; and a second power supply component mounted in a wire feederhousing and comprising: a power conversion module to convert said secondfixed DC output signal to a welding output for welding in said process,wherein the power conversion module in the wire feeder housing isoperatively connected to receive at least one of a voltage feedbacksignal of the welding output and a current feedback signal of thewelding output at the wire feeder housing, and regulate the weldingoutput based on the at least one of a voltage feedback signal of thewelding output and a current feedback signal of the welding output, anda wire feeding module which controls the operation of a wire feedermechanism within the wire feeder housing; wherein each of said first andsecond power supply component have a separate housing structure, whereinsaid second power supply component is positioned remote from said firstpower supply component and said second fixed DC output signal of saidsecond stage is maintained over a set of power cables which couples saidfirst power supply component to said second power supply component. 2.The power supply system of claim 1, wherein said set of power cableshave a length in the range of 100 to 500 feet.
 3. The power supplysystem of claim 1, wherein said input stage includes a rectifier and apower factor correcting converter.
 4. The power supply system of claim1, wherein said power conversion module includes a chopper with a powerswitch operated at a given frequency.
 5. The power supply system ofclaim 4, wherein said chopper is a dual mode chopper with a firstpolarity path with a first power switch and a first polarity switch anda second polarity path with a second power switch and a second polarityswitch, wherein the first polarity path and the second polarity path areopposite polarity paths between an electrode and a workpiece, and thedual mode chopper is selectively operable in any one of an AC mode, a DCpositive mode, and a DC negative mode.
 6. The power supply system ofclaim 5, including a controller within said second power supplycomponent with a first mode alternately operating said chopper betweenfirst and second polarity paths and a second mode operating said chopperin only one of said polarity paths.
 7. The power supply system of claim1, wherein said power conversion module includes a circuit, located inthe wire feeder housing, with a power switch to perform an STT weldingprocess.
 8. The power supply system of claim 1, wherein said wirefeeding module receives power from said second fixed DC output signal.9. A power supply system for an electric arc welding process, said powersupply system comprising: a first module including: an input stagehaving an AC input and a first fixed DC output signal; a second stage inthe form of an unregulated DC to DC converter, unregulated by a feedbacksignal from the electric arc welding process, having an input connectedto said first fixed DC output signal, a network of switches switched ata high frequency with a given duty cycle to convert said input into afirst internal high frequency AC signal, an isolation transformer with aprimary winding driven by said first internal high frequency AC signaland a secondary winding for creating a second internal high frequency ACsignal; and a smoothing choke and a rectifier to convert said secondinternal high frequency AC signal into a second fixed DC output signalof said second stage, said second stage having a fixed relationshipbetween input and output voltages of the second stage; and a secondpower supply component mounted in a wire feeder housing and comprising:a power conversion module to convert said second fixed DC output signalto a welding output for welding in said process, wherein the powerconversion module in the wire feeder housing is operatively connected toreceive at least one of a voltage feedback signal of the welding outputand a current feedback signal of the welding output at the wire feederhousing, and regulate the welding output based on the at least one of avoltage feedback signal of the welding output and a current feedbacksignal of the welding output, and a wire feeding module which controlsthe operation of a wire feeder mechanism within the wire feeder housing;wherein each of said first module and said second power supply componenthave a separate housing structure, wherein said second power supplycomponent is positioned remote from said first module and said secondfixed DC output signal of said second stage is maintained over a set ofpower cables which couples said first module to said second power supplycomponent.
 10. The power supply system of claim 9, wherein said set ofpower cables have a length in the range of 100 to 500 feet.
 11. Thepower supply system of claim 9, wherein said input stage includes arectifier and a power factor correcting converter.
 12. The power supplysystem of claim 9, wherein said power conversion module includes achopper with a power switch operated at a given frequency.
 13. The powersupply system of claim 12, wherein said chopper is a dual mode chopperwith a first polarity path with a first power switch and a firstpolarity switch and a second polarity path with a second power switchand a second polarity switch, wherein the first polarity path and thesecond polarity path are opposite polarity paths between an electrodeand a workpiece, and the dual mode chopper is selectively operable inany one of an AC mode, a DC positive mode, and a DC negative mode. 14.The power supply system of claim 13, including a controller within saidsecond power supply component with a first mode alternately operatingsaid chopper between first and second polarity paths and a second modeoperating said chopper in only one of said polarity paths.
 15. The powersupply system of claim 9, wherein said power conversion module includesa circuit, located in the wire feeder housing, with a power switch toperform an STT welding process.
 16. The power supply system of claim 9,wherein said given duty cycle is adjustable.
 17. The power supply systemof claim 9, wherein said input stage has a power factor correctingconverter which is a buck+boost converter.
 18. The power supply systemof claim 9, wherein said wire feeding module receives power from saidsecond fixed DC output signal.